Microsoft said a Russian-linked hacking group attacked its corporate systems, getting into a “small number” of email accounts, including those of senior leadership and employees who work in cybersecurity and legal. The company said it’s acting immediately to fix older systems, which will probably cause some disruption. The hacking group doesn’t appear to have accessed customers’ systems or Microsoft servers that run outward-facing products, the software giant said Friday in a blog post. Microsoft also has no evidence the group, named Midnight Blizzard, got into source code or artificial intelligence systems. “We will act immediately to apply our current security standards to Microsoft-owned legacy systems and internal business processes, even when these changes might cause disruption to existing business processes,” the company said. “This will likely cause some level of disruption.” The group that Microsoft deemed responsible, also known as “Nobelium,” is a sophisticated nation-state hacking group that the US government has tied to Russia. The same group previously breached SolarWinds, a US federal contractor, as part of a massive cyber-espionage effort against US federal …